We have two bits of information that we received separetely, yet tell a nice story.
First, we just heard from a fairly well known commercial software company who make an app for Windows Phone (as well as Android and iOS), that the Mango release/update has been delayed:
"The (omitted) Windows dev team has just learned that Mango is delayed until September 15th."
We were surprised to receive that info because (a) we didn't know what the previous date was (September 1st?) and (b) we didn't even inquire about it. Once again, this isn't an indie developer but a commercial software company who works with Microsoft directly, so we take their word as truth on the matter. However, we're still not 100% clear on what that means exactly.
Second, the other information comes from an online chat with an HTC customer service rep and a user of the popular Chinese forum WPXAP (they're like a Chinese XDA). Normally we discount CS rep information, but here the info is detailed and interestingly jives with the information from above. In short, the release date is in September, but they were not ready to reveal the exact date. When we say "the release" it looks to be the update release, not just for new devices. HTC has received the RTM version, they are applying patches and working with Microsoft on final verification before release.
Makes sense and with the "delayed till Sept 15th" info previously mentioned, it all comes together for us. Is it a guarantee? Nope, but we feel this is close to something.
Update: Lets add a 3rd bit of info. Back in July we speculated that the AT&T Dell Venue Pro was not going to re-ship till end of August due to it getting a Mango update (it's been "out of stock" for weeks). Now if you go to that page the preliminary ship date is...wait for it...September 15th. Thanks, Azolo, in comments!
WPXAP info via WeLoveWP